The item that is, Standing Up, is a penis. The song tells about a man waking up in the morning, after a night of passion, and he's still thinking about that passion from the night before. He notices the naked girl next to him, and things begin, well, to Stand Up. The "vein" begins to cook, and he has every intention of "shoot-ing you up again". With that, you can probably figure out what "... drop me in the water, lift me up and save my soul" means.